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Mind-controlled permanently-attached prosthetic arm could revolutionize prosthetics

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November 29, 2012

Max Ortiz Catalan demonstrates how the system works with the aid of electrodes placed on t...

Max Ortiz Catalan demonstrates how the system works with the aid of electrodes placed on the skin, although amputees will have the electrodes implanted directly on the nerves and muscles inside the body

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Researchers based at Chalmers University of Technology in Sweden have developed the world’s first thought-controlled, fully implantable robotic arm, which uses an amputee's own nerves and remaining muscles to afford a much more intuitive level of control than previously possible. Initial operations on patients are scheduled to take place during the Northern Hemisphere’s upcoming winter.

Prosthetic limbs which are controlled by electrical impulses in the muscles have been available to amputees since the 1960’s, but they tend to be limited in function and difficult to control. Additionally, many amputees find the standard method of using a tightly fitted socket to attach the prosthetic limb to the body so uncomfortable, that they choose to simply forgo using one altogether.

Keen to maximize the comfort and intuitiveness of their design, the Chalmers researchers looked to a process known as osseointegration. Originally developed in the 1960‘s, osseointegration involves joining living bone to the surface of an artificial implant, and has been used successfully for ear, eye, and nose prosthetics, in addition to larger limb prosthetics.

“Osseointegration is vital to our success,” explained Max Ortiz Catalan, industrial doctoral student at Chalmers University of Technology in Sweden. “We are now using the technology to gain permanent access to the electrodes that we will attach directly to nerves and muscles.”

A diagram of Chalmers' implanted prosthetics system

A titanium implant will be anchored directly to the patient’s skeleton, and feature electrodes which join onto the remaining nerves and muscles of the amputee. Employing the electrodes in this way affords a significantly increased signal stability when compared to the typical method of controlling prostheses, which involves placing electrodes on the skin’s surface.

Electrical impulses are to be captured from the subject’s nerves with the implanted electrodes, before being transferred to a neural interface, which in turn transmits these impulses through the osseointegrated titanium implant. Finally, the impulses are decoded by sophisticated algorithms within the artificial arm, which help give the subject fine control over movements.

The artificial hand itself is very dexterous. Motors in each finger can be controlled both individually and simultaneously, allowing greater freedom of movement than was possible until now. The artificial hand also gives a level of feedback as the electrodes stimulate the neural pathways to the patient’s brain – presumably in way similar to real limbs. This contrasts with the more typical and inexact method of relying on auditory or visual feedback from an artificial hand’s motors to estimate the grip force.

The first operations on human patients will take place during the Northern Hemisphere’s upcoming winter, and Catalan and his colleagues hope that, following a successful demonstration, their technology will eventually be used more widely.

The video below (which uses the less exact skin-based electrodes for the sake of demonstration), looks very promising, and should the human trials prove successful, the new prosthesis system could potentially change the lives of many amputees.

Source: Chalmers University of Technology

About the Author
Adam Williams Adam scours the globe from his home in North Wales in order to bring the best of innovative architecture and sustainable design to the pages of Gizmag. Most of his spare time is spent dabbling in music, tinkering with old Macintosh computers and trying to keep his even older VW bus on the road.

  All articles by Adam Williams
4 Comments

wow, that looks like a huge improvement to the current ones available. I hope they refine it enough for the market in the coming years.

Derek Howe
29th November, 2012 @ 05:10 pm PST

Very Interesting but what sort of materials are going to be used with the electrodes being implanted. I think I saw a new material a few months back on Gizmag that might be useful. They used it on a catheter which the body did not try to kill and which did not lead to infection. Will that be a problem for this sort of thing?

Spriscilla the Queen of the Ocean
29th November, 2012 @ 06:42 pm PST

I also think there is a whole range of wireless technology that would be great to integrate into this product. As well as a range of new sensors. I am working on one myself which uses a nano piezoelectric sensor network embedded in a dillitant skin, or another sensor that is not identified which monitors voltage changes in the dillitant. I plan to use this with a UK companies flexi plastic with nano particles of metals that react to pressure which increases the voltage that is able to run through the skin (http://www.peratech.com/tools.php). The basic Idea was for the piezo component to sense impacts and pressure which could be relayed in this case back to the appropriate nerve pathways. A japanese guy came up with a similar idea that uses a dillitant in the optic fibre network. http://www.sumobrain.com/patents/wipo/Improvements-in-fibre-optic-cables/WO2012028845.html

I decided to share this knowledge that I am having trouble developing.

Spriscilla the Queen of the Ocean
29th November, 2012 @ 06:59 pm PST

Would this possibly help not only amputees, but also people who were born with missing limbs?

valerie
30th November, 2012 @ 05:58 pm PST
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